EUROPEAN SOUTHERN OBSERVATORY Organization Europeene´ pour des Recherches Astronomiques dans l’Hemisph´ ere` Austral Europaische¨ Organization f¨ur astronomische Forschung in der s¨udlichen Hemisphare¨ ESO - European Southern Observatory Karl-Schwarzschild Str. 2, D-85748 Garching bei M¨unchen Very Large Telescope Paranal Science Operations VIRCAM/VISTA User Manual Doc. No. VLT-MAN-ESO-xxxxx-yyyy Issue 85.0, Date 18/12/2009 V. D. Ivanov, T. Szeifert Prepared ................................................ Date Signature A. Kaufer Approved ................................................ Date Signature C. Dumas Released ................................................ Date Signature ii VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy This page was intentionally left blank VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy iii Change Record Issue/Rev. Date Section/Parag. affected Reason/Initiation/Documents/Remarks 0.1 09/09/2008 All Creation 1.0 xx/xx/2009 All First public release. iv VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy This page was intentionally left blank VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy v Contents 1 Introduction 1 2 Applicabledocumentsandothersourcesofinformation 3 3 Abbreviations and Acronyms 5 4 VISTA and VIRCAM in a nut-shell 6 5 The VISTA Telescope – Technical Description 7 6 The VIRCAM - VISTA Infra-Red Camera 9 6.1 Generalfeatures ................................. ...... 9 6.2 Detectors ....................................... .... 11 6.3 Filters ......................................... .... 13 6.4 Sensitivity..................................... ...... 17 6.5 LowOrderWavefrontSensorsandAutoguiders . ............ 17 6.6 HighOrderWavefrontSensorOperation . ........... 18 7 Observations with VIRCAM@VISTA 20 7.1 ObservationsintheInfrared . .......... 20 7.1.1 TheInfraredSky ................................ ... 20 7.1.2 SelectingthebestDITandNDIT . ...... 21 7.2 Preparation for observations and general operation of VIRCAM@VISTA ........ 22 7.3 Pawprints, Tiles, Jitters, Microsteps . ............... 24 7.3.1 Definitions.................................... ... 24 7.3.2 “Filling-in” a tile with multiple pawprints . ............... 25 7.4 SchedulingContainers. ........ 27 7.5 ObservingStrategy,Nesting. .......... 28 7.6 AutoguidingandAOoperation . ........ 30 7.7 Overheads ....................................... ... 30 7.8 CalibrationPlan................................. ....... 31 7.8.1 Instrumentsignatureremoval . ........ 32 7.8.2 PhotometricCalibration . ....... 36 7.8.3 AstrometricCalibration . ....... 38 7.8.4 Additional Calibrations Derived from Science Data . .............. 40 8 Data Flow, Pipeline, Quality Control 41 9 References and Acknowledgments 45 A VISTA/VIRCAM Template Reference 46 A.1 RecentModificationsoftheTemplates . ........... 46 A.2 Introduction to the Phase 2 Preparation for Public Surveys................ 46 A.3 The Acquisition Templates – VIRCAM img acq tile and VIRCAM img acq quick. 47 A.4 TheScienceObservationYemplates . .......... 49 vi VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy A.4.1 VIRCAM img obs tile<N> ............................. 49 A.4.2 VIRCAM img obs paw ............................... 57 A.5 The Calibration Templates – VIRCAM img cal illumination and VIRCAM img cal std . 57 A.6 TemplateParameterTables . ........ 57 B VISTA/VIRCAM Observing Blocks Cookbook 63 C VISTA@VIRCAM FITS Header Description 65 VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy 1 1 Introduction VISTA or Visible1 and Infrared Survey Telescope for Astronomy is a specialized 4-m class wide field survey telescope for the Southern hemisphere. VISTA is located at ESO Cerro Paranal Observatory in Chile (longitude 70o 23’ 51”W, latitude 24o 36’ 57” S, elevation 2500 m above sea level) on its own peak about 1500m N-NE from the Very Large Telescope (VLT). The telescope has an alt-azimuth mount, and quasi-Ritchey-Chretien optics with a fast f/1 primary mirror giving an f/3.25 focus ratio at the Cassegrain focus. It is equipped with a near infrared cam- era VIRCAM or VISTA InfraRed Camera (with a 1.65 degree diameter field of view (FOV) at VISTA’s nominal pixel size) containing 67 million pixels of mean size 0.339 arcsec × 0.339 arcsec. The in- strument is connected to a Cassegrain rotator on the back of the primary mirror cell, and has a wide-field corrector lens system with three infrasil lenses. The available filters are: broad band ZYJHKS and a narrow band filter at 1.18micron. The point spread function (PSF) of the tele- scope+camera system delivers images with a full width at half maximum (FWHM) of ∼0.51 arcsec (without the seeing effects). The weather characteristics and their statistics are similar to those for the VLT. VISTAhas one observing mode - imaging - and the telescope is used mostly in service mode to carry out surveys - programs exceeding in size and scope the usual ESO Large Programs. Typically, the observations are carried out in a 6-step pattern, called tile, designed to cover the gaps between the individual detectors. The high data rate (on average 315GB per night) and the large size of the individual files (256.7 MB) makes it a significant challenge for an individual user to cope with the data reduction challenges. The VISTA raw data are available via the ESO archive. High-level data products (i.e. photometry, catalog with object classification and derived physical parameters, etc.) are also available via the ESO archive for the ESO Public Surveys. This manual is divided into several sections, including a technical description of the telescope and the camera, a section devoted to the observations with VISTA, including general information about the nature of the infrared sky, the operation of VISTA, the sensitivity of the instrument and a (prelimi- nary) calibration plan. Next, the manual summarizes the data flow, the pipeline, and the parameters that are used for the quality control. Finally, the Appendix contains a template reference guide. This manual was based on many documents, kindly provided by the VISTA consortium. The authors hope that you find it useful in your VISTA observations. The manual is continuously evolving with the maturing of the telescope and there will always be room for improvement. Comments from the users are especially welcomed. Please, refer to the ESO VISTA web site for contact details. Nota Bene: • The web page dedicated to VISTA is accessible from the La Silla Paranal Observatory home page at: http://www.eso.org/sci/facilities/paranal/instruments/vista/ You will find there the most up-to-date information about VISTA, including recent news, effi- ciency measurements and other useful data that do not easily fit into this manual or is subject 1A wide field visible camera was considered during the early stages of VISTA development, accounting for the visible component to the telescope name. 2 VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy of frequent changes. This web page is updated regularly. An external (with respect to ESO) source with history of the project and relevant information is the VISTA consortium web-page at: http://www.vista.ac.uk/index.html • Please, read the User Manual! It is located at: http://www.eso.org/sci/facilities/paranal/instruments/vista/doc/ • Contact information: for questions about VISTA and VIRCAM write to [email protected]; for questions about the service mode observations write to [email protected] VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy 3 2 Applicable documents and other sources of information Documents: • VLT-MAN-ESO-00000-0000 OS Users’ Manual • VLT-MAN-ESO-00000-0000 DCS Users’ Manual • VLT-MAN-ESO-00000-0000 ICS Users’ Manual • VLT-MAN-ESO-00000-0000 P2PP Users’ Manual • VLT-MAN-ESO-00000-0000 SADT Users’ Manual Web sites: • ESO VISTA main page: http://www.eso.org/sci/facilities/paranal/instruments/vista/ • VISTA operation team contact list: http://www.eso.org/sci/facilities/paranal/instruments/vista/iot.html • ESO Public Surveys: http://www.eso.org/sci/observing/policies/PublicSurveys/sciencePublicSurveys.html • ESO Data Archive: http://archive.eso.org/cms/ • ESO P2PP Tool for Surveys: http://www.eso.org/sci/observing/phase2/P2PP/P2PPSurveys.html http://www.eso.org/sci/observing/phase2/P2PP/P2PP3Documentation.html • ESO SADT page: http://www.eso.org/sci/observing/phase2/VIRCAM/SADT.html • VISTA SADT page: http://www.vista.ac.uk/observing/sadt/index.html • VISTA Science Archive (at ROE): http://horus.roe.ac.uk/vsa/www/vsa browser.html • VISTA Science Verification: http://www.hq.eso.org/sci/activities/vltsv/vista/ • VISTA Consortium: http://www.vista.ac.uk/index.html • VISTA at UK Astronomy Technology Centre: http://www.roe.ac.uk/ukatc/projects/vista/eso.html • Cambridge Astronomical Survey Unit (CASU): http://casu.ast.cam.ac.uk/ http://www.ast.cam.ac.uk/∼mike/casu/index.html 4 VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy • VISTA Data Flow System (VDFS; at CASU): http://www.ast.cam.ac.uk/vdfs/ www.maths.qmul.ac.uk/∼jpe/vdfs/ • Wide Field Astronomy Unit (WFAU): http://www.roe.ac.uk/ifa/wfau/ • Astronomical Wide-field Imaging System for Europe (Astro-WISE): http://www.astro-wise.org/ • Deep Near Infrared Survey of the Southern Sky (DENIS): http://cdsweb.u-strasbg.fr/denis.html • The Two Micron All Sky Survey (2MASS; at IPAC): http://www.ipac.caltech.edu/2mass/ • UKIRT IR Deep Sky Survey: http://www.ukidss.org/ VIRCAM/VISTA User Manual VLT-MAN-ESO-xxxxx-yyyy 5 3 Abbreviations and Acronyms The abbreviations and acronyms used in this manual are described in Table 1. Table 1: Abbreviations and Acronyms used in this manual. ADU